绣球属(Hydrangea L.)及近缘属花粉形态的研究

Pollen morphology of Hydrangea L.( Hydrangeaceae) and its related genera

为深入研究绣球属植物花粉形态的分类学价值和系统学意义,厘清绣球属与近缘属之间的系统发育关系,该文利用扫描电子显微镜(SEM,scanning electron microscope)对国产绣球属及其近缘属41种绣球花科(Hydrangeaceae)植物的花粉形态以及表面纹饰进行了观察。结果表明:绣球属及其近缘属的花粉为三孔沟;形状多数为长圆体形或近球体形;赤道面观为椭圆形或圆形;极面观多为圆形,少数为三角形或圆三角形。花粉外壁纹饰可分为网状和孔穴状。网眼内的三级纹饰可分为光滑和具颗粒状突起。根据花粉形状和外壁纹饰类型将上述物种划分为4个组,即花粉的形状为长圆体形,表面纹饰为孔穴纹饰;花粉的形状为长圆体形,表面纹饰为网状纹饰;花粉的形状为近球体形,表面纹饰为孔穴纹饰;花粉的形状为近球体形,表面纹饰为网状纹饰。以上可进一步细分为8个类型。上述表明花粉形态证据可为绣球属及其近缘属的属下分类和种间界定提供重要佐证;但结合前人的系统发育重建分析该属植物花粉形态的系统学意义相对有限,如花粉形态证据对于该属及其近缘种属系统发育树上大支的界定难以提供有力的证据。

In order to study taxonomic value and systematic significance of Hydrangea L.as well as clarify phylogenetic relationships among the genus and its related ones,pollen samplings of 41 species of Hydrangea and its related species from China and surrounding areas were observed under scanning electron microscope(SEM).The results were as follows:the pollens of all these species were tricolporate;the pollen morphology were most subprolate and a few subspheroida;ellipse or circular in equatorial view;circular or sometimes triangular in polar view.The ornamentations on the exine can be reticulate ornamentations or perforate ornamentations.The ornamentation in the mesh could be smooth or granular bulged.The above-mentioned species could be divided into four groups according to the pollen morphology and ornamentations on the exine,the characters of each group were respectively pollen morphology subprolate,ornamentation on the exine reticulate;pollen morphology subprolate,ornamentation on the exine perforate;pollen morphology subspheroida,ornamentation on the exine reticulate;pollen morphology subspheroida,ornamentation on the exine perforate.according to the ratio of polar axis to equatorial axis,these species can be further divided into eight types.These indicate that the pollen characters can provide valuable evidence for infrageneric taxonomic treatments and species circumscription.However,this evidence shows limited value in diagnosing some major clades of phylogenetic trees reconstructed in previous studies.Further studies including broader sampling and new evidence of Hydrangea pollen are needed to explore its taxonomic and systematic values.